handle count(*) in `having` correctly

[seebs]

After tracking through a whole bunch of unrelated code and coming up with a 40-line patch that mostly fixed this, I realized that the fact that it worked for count(field) meant something was making it work, added countStarPlanExpression to that case, and magically everything got better.

Writing one line of code: 30 seconds Figuring out which one line of code to write: two days

[seebs]

@tgruben, tagged you on review because Pat looked at the original second commit, figured out it was wrong, and fixed it, so now the second commit in particular needs someone else to look at it and verify that this makes sense.

[sonarcloud[bot]]

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